Issue 38

This is in fact a first try. I cleaned up the file a bit, tried to be consistent, removed some dups... But I'm still not sure that descriptions (or even names) are accurate, and for sure many metrics are missing. However, I'm not sure it makes sens to clean up this much more until we systematize the design and definition of variables in the new API.
In any case, I would close #38 with this patch.